A number of recent studies have suggested that
icariin (ICA), a class of
phytochemical with numerous
biological activities, may exert protective effects against
postmenopausal bone loss. However, it remains unclear whether ICA regulates or improves the osteoblastic function of bone marrow stromal cells (BMSCs) in the treatment and prevention of
osteoporosis. In the present study, the osteogenic differentiation of BMSCs from
ovariectomy (OVX) rats was found to be significantly decreased in vitro compared with that in rats that had undergone a
sham operation. Treatment with ICA at a dose of 10-5 M was shown to restore the osteogenic differentiation of BMSCs in OVX rats. The results indicated that ICA restored the differentiation and mineralization capacity of OVX-BMSCs, which had been induced by
estrogen deficiency. The effects of this compound on
alkaline phosphatase (ALP) activity and
calcium deposition were also measured at various time points. The number of colonies and areas that stained positive for ALP expression, and mineralized bone nodules were analyzed histochemically at 14 and 21 days after the osteogenic induction. The expression of the runt-related
transcription factor 2 and osterix bone metabolism
biomarker proteins and genes were detected by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression of factors involved in the
estrogen signaling pathway,
estrogen receptor α (ERα),
progesterone receptor (PR) and
trefoil factor 1 (PS-2), was also detected by western blotting and RT-qPCR. ICA enhanced the expression of ERα, PR, PS-2 in OVX‑BMSCs, but this effect was abrogated when
ICI 182780, an ER antagonist was added.
Transplantation of BMSCs into nude mice demonstrated that ICA restored the osteogenic capability of OVX‑BMSCs in vivo. Therefore, it may be that ICA acts through the
estrogen pathway in order to improve and restore the osteogenic differentiation and mineralization of OVX‑BMSCs, which are inhibited by
estrogen deficiency and increasing age.